Dewaxing of oil



L. D. JQNES DEWAXING OF OIL @cfz. 17,

U U u 0 0000600006 Filed Dec.

Patented Oct. 17,1933

PATENT OFFICE DEWAXING or on.

Leo D. Jones, Philadelphia, Pa., assignor a The Sharples Specialty'Company,

Philadelphia,

Pa., a corporation of Delaware Application December 23, 1927 Serial No.242,028

11 Clims.

This invention relates to a process for the removal of wax frompetroleum products, the term fpetroleum products being used herein todesignate the substances that may be dewaxed in accordance with thisinvention andincluding crude petroleum oils from various sources, andmixtures thereof, and distillates or residues or other fractions orintermediate or final'products occurring in or resulting fom therefining of crude petroleums, and mixtures thereof.

One aspect of this invention is that it is an improved centrifugalprocess for the dewaxing of petroleum products, but important featuresof the. invention are not limited to that point of view and are ofgeneral application in the dewaxing of petroleum products by otherprocesses.

The known practice in the removal of wax from petroleum products is as awhole subject to numerous limitations and'to many dimculties. In

known practice wax has been removed from petroleum products by filterpressing and by cold settling and more recently, but on a large scaleand more completely and more rapidly, by centrifugal separation. In eachof these methods the wax is precipitated, preperatory' to its removal,by chilling 'the product or mixture from which the wax is to be removed,the mixture be- I ing especially fluid prior to chilling because of veither added naphtha or light petroleum products formed in thepreparation,as by cracking distillation, of the product to be dewaxed;and it has been proposed to add to the'oil-naphtha solution foreignparticles to which wax may adhere. but in that operation one of, severaldifliculties is the removal of theparticles from whatever wax adheres tothem. Butv each of these .methods of removing wax from petroleumjssubject to numerous limitations and to various de-o gres of difliculty.If a wax-containing petroleum product is merely chilled, with or withoutdilution, to precipitate the wax, filter pressing can only be employedto remove the preciptated wax when it is distinctly crystalline innature, as in the case of cracked distillates.

is subjected to further cracked distillation or maybediluted withnaphtha. Cold settling can only be employed when the wax precipitated bychilling is distinctly amorphous in nature, as in the case Crystallinewax-containing fractions of crudepetroleum are settle. Ordinarycentrifugal dewaxing of petro-' leum products, consisting of dilutingwith naphtha and chilling and centrifugally removing, with the use of acarrier liquid, the precipitated wax, has been highly successful inremoval of wax that is distinctly amorphous when precipitated and iscapable of dewaxing certain distillates and the long residuum (theresidue after removal of gas, naphtha and burning oil) of some crudeoils. Other petroleum products can be dewaxed successfully bycentrifugal methods which involve special steps whereby the particularcharacteristics of the wax are taken into account. When some. petroleumproducts are merely mixed with naphtha and chilled the precipitated waxis neither sufliciently crystalline to be rev such wax is heavier thanthat solution and large! lyjamorphous and such petroleum products cannot be dewaxed by processes depending upon' differences betweenthe'specific gravity of the oil and the wax, orby filtering.- It hasbeen' common practice to subject such petroleum products to crackingdistillation to bring the wax content into crystalline form but thatstep has resulted in considerable losses due-to conversion of largefractions of the oil into nonlubricating oils. Such petroleum productsmay be dewaxed centrifugally when naphtha is employed as a solventprovided special processes are used and carried out with considerablecare. lf'naphtha, of especially low specific gravity is used in order toreduce the specific gravity of the oil-naphtha'solution after chilling,for the purpose ofcausing the oil-naphtha solution to be lighter thanall of the precipitated wax'or for the purpose of increasing thedifference between the specific gravities of the wax ands lution, largeevaporation losses occur, partic rly in the' heating of the mixturepreparatory to the chilling. If, theproportion' of naphtha, used as asolvent, that is added to the wax-containoil product.

ing product prior to chilling is increased for the purpose of reducingthe specific gravity of the oil-naphtha solution to a value below thatof light constituents of the wax precipitated by chilling, the cold testof the final oil is impaired because there is less oil in the resultingoilnaphtha solution and the wax that remains in solution in theoil-naphtha solution after chilling remains in solution in that reducedquantity of oil after naphtha is distilled therefrom and produces anunusually high wax content in the final In commercial operation filterpressing produces oil having a cold test of 25 F. to 30- F. and coldsettling produces oil having a cold test of about 50 F., and ordinarycentrifugal dewaxing produces oil with a cold test of 15 F. to 25 F.Other limitations and-defects in the known practice of dewaxingpetroleum are well known to those skilled in the art and some of suchdefects and limitations will be referred to hereinafter.

It is an object of this invention to provide a process for the dewaxingof petroleum products in which the defects and limitations of priorpractice are eliminated or minimized. Other and further objects andadvantages of my invention will appear from the following description orwill be apparent, in the light of such description, to those skilled inthe art.

In accordance with my invention, wax-containing petroleum products arediluted with an oil solvent that is of such character and is present insuch proportion that all of the wax precipitated by chilling, of themixture is lighter than the residual solvent-oil solution, and then thewax is precipitated by chilling and separated from the solvent-oilsolution. The dewaxed oil is recovered from the solvent-oil solution inany suitable manner, as by distillation, and the wax is freed of solventin any suitable manner. Thus, in the practice of my invention theprecipitated wax rises to the surface of the chilled mixture under theaction of gravity or accumulates in the inner zone of the centrifugalbowl. Inprior practice an effort to have the solvent-oil solutionlighter than wax precipitated therein limited the solvents used incommercial practice to light petroleum products. With such lightsolvents some of the wax in the product to be dewaxed might be lighterthan the solvent-oil solution and the remainder of the wax heavier. Insuch case the use of a lighter solvent caused evaporationlosses, and useof a greater proportion of solvent carried an undesirably large quantityof wax in the oil finally produced. In some of such cases neither theuse of lighter solvent nor the use of a greater proportion of solventwould cause the solvent-oil solution to be lighter than all of' the waxand the wax could not be removed from such a mixture by gravity or bycentrifuging, and usually, in such a case, the precipitated wax couldnot be separated by filter pressing because it would be too amorphous asa whole. Thusjin former practice there were limitations upon'therelative lightness of the solvent and those limitations imposed furtherlimitations upon the kinds of wax that could be separated by particularoperations. But, in accordance with my invention a solvent is selectedthat willcause all of the precipitated wax, regardless of its character,to be lighter than the solvent-oil solution." Thus, solvents may be soselected that the difference between the specific gravities of the waxand of the oil-solvent solution are relatively great as compared withthe difference between the specific gravities of the wax and of theoil-naphtha solution. This difference of specific gravities is alwaysnecessarily small when naphtha is employed as a solventand sometimes thespecific gravity of the oil-naphtha solution is intermediate of thespecific gravities of different constituents of the wax present. Againsolvents used in the practice of my invention may be less volatile thanthe naphtha ordinarily employed and much less volatile .than the lightnaphthas employed in the dewaxing of oils containing some relativelylight wax. The difference be tween the specific gravities of the wax andof the oil-solvent solution being obtained by selection of the solvent,it is not necessary in the practice of my invention to use excessivequantities of solvent or to use very light solvent that is undesirablyvolatile or to adopt both of those expedients in order to obtain thenecessary difference of specific gravities, and the objectionableresults of those expedients are avoided.

Examples of solvents that may be used in the practice of my inventionare gas-oil, benzene, dichlor ethane, carbon tetrachloride, dichlorpropane, carbon disulphide, chlor benzene, etc. A distinct advantage ofusing such solvents is that a solvent may be selected that contains lesswax in solution after precipitation of the wax by chilling than iscontained in light petroleum products formerly employed. Thus, in thepractice of my invention a solvent may be used that has a greaterdiiferential solubility as between wax and oil, especially attemperatures employed in commercial dewaxing, than solvents of thelimited field heretofore employed. Furthermore, with the use of suchsolvents, in the practice of my invention, the chilling for theprecipitation of wax does not always have to be carried to 'as low atemperature as mixtures of 'oil and naphtha, to produce oils of evenlower. cold test than oils produced by using light petroleum products assolvents and chilling to much lower temperatures. Moreover, while thesolvents heretofore used have been limited to light petroleum productshaving a specific gravity up to 55 Baum, solvents employed in thepractice of my invention are not limited topetroleum products andtherefore solvents may be employed that have characteristics differinggreatly from light petroleum products, and a solvent may be selectedthat has characteristics best, suitedfor the separa tion of wax from theparticular oil that is being handled. Also, in the practice of myinvention it becomes possible to use solvents consisting of mixtures ofsubstances, each of. which possesses some property that contributestoward the efliciency or economy of the dewaxing operation. When lightpetroleum products have been used as solvents it has been-necessary toexercise care in chilling the mixture in order to avoid any suddenlowering of the temperature thereof, but in using solvents contemplatedin my invention, and particularly ethyl- "ene dichloride, good resultshave been obtained with various rates of chilling and the precipitationis not as sensitive to variations in chilling asin the case when naphthais employed. 4 In all dewaxing processes involving the addition orpresence ofa solvent it is important that the chilled solution besufficiently fiuid to facilitate'the removal of wax therefrom. But it isdesirable and is entirely possible in the practice of my invention toavoid using a proportion of solvent in excess of thisrequirement.Increasing the proportion of solvent beyond that which is necessary tomeet this requirement increases the amount of wax that phous for oneoperation or too crystalline for the other or because the naphtha-oilsolution can-. not practicably be made lighter than all of theprecipitatedwax, losses occuring in the early practice of subjecting theoil to cracking distillation to bring the wax to -a crystallinecondition have largely been avoided by later practice. In such laterpractice the wax in such oils is brought as a whole to a condition inwhich it is all heavier than an oil-naphtha solution after chilling andin which it can readily be discharged from the centrifuge, thiscondition being achieved by adding amorphous wax or oil containingamorphous wax or by adding or otherwise adjusting or regulating thecontent of color-forming impurities that occur in petroleum oil, or inresorting to'two or more of such expedients, centrifugal separationemploying acarrier liquid being preferably for the removal of such waxfrom such a mixture. But, in accordance with my invention petroleumprodf ucts containing wax of such characteristics maybe dewaxed withoutcracking and without using such special steps, because the precipitatedwax can be caused to be lighter than the oil-solvent solution byselecting a suitable solvent that is not undesirably volatile and needonly be used in economical proportions. By the practiceof my inventionit is readily possible to obtain petroleum oils and particularlylubricating oils having 'a cold test of zero degrees pressing, coldsettling or centrifugal separationis employed.

My invention is generally applicable to the dewaxing of. petroleumproducts, and, while it is not limited to the centrifugal removal of waxfrom-the chilled mixture, it is particularly adapted to that type of waxremoval. In centrifugal dewaxing the above described advantages and manyother advantages of my invention are obtainedf' p In the centrifugalseparation of precipitated wax from a chilled solution of oil, whennaphtha has been used as the solvent, the wax constitutes the heavierconstituent and several difficulties arise that are avoided in thepractice of my invention. The centrifugal bowl contains a dividing wallthrough the center of which the lighter constituent of a mixture isdirectly discharged through a relatively simple passage. The dividingwall extends radially outward to a point near the inner surface of thebowl, and when wax is the heavier constituent in the mixture a carrierliquid is employed that fills the outer zone of the bowl and engages theouter edge of the dividingwall and forms a liquid surface facilitat--ing the movement of wax that might adhere to the inner surface of thebowl; and a body ofcarrier liquid occupies the space between thedicharged.

viding Wall and the end of the bowl and maintains hydraulic balance withthe wax and oil in the main body of the bowl. Thus, when wax is theheavier constituent it must pass around the outer edge of the dividing,wall and up through the carrier liquid in the auxiliary compartment andthen -pass through relatively complicated dischargepassages. Whennaphtha is used as a solvent it is necessary that the naphtha-oilsolution shall all be lighter than the precipitated wax and necessarythat the wax be capable of passing around the edge of the dividin walland through the discharge passages, even though the presence ofcrystalline wax and hard asphalt impose difiiculties upon the dischargeof wax from the centrifugal bowl. To avoid these difiiculties it hasbeen necessary at times to use excessively light solvent or excessivequantities of solvent necessary to remove hard asphalt by mild acidtreatment preliminary to centrifugal dewaxing.

The complicationscin the discharge passage for the heavier substancefrom the centrifuge make it difficult to apply heat in such a way as toassist the discharge of crystalline wax or hard wax, or hard asphalt,without heating the contents of the bowl and thereby impairing the waxseparation.

' In the practice of my invention the wax is lighter thanthe solvent-oilsolution and there- .fore passes to the central zone of the centrifugeand is discharged directly through thg relatively simple dischargepassage leading therefrom while I the wholly-liquid solvent-oil solutionpasses to the outer zone and flows through the more or less complicateddischarge construction. The discharge of wax from the central zone ofthe centrifug'e' imposes fewer difficulties upon the discharge ofhardand crystalline wax and asphalt and affords greater opportunity forthe application of any necessary heat toa substance so dis The use ofcarrier the .practice of my invention in which the wax discharges fromthe central zone of the bowl.

It will now be apparent that the difiiculties of centrifugal dewaxingdue to the presence of crystalline wax or-asphalt, or due torelativelightness of some part of the wax or variations in the specificgravity of different constituents of the liquid is not necessary in wax,areavoided by my invention and that the use of carrier liquid isdispensed with and that it becomes relatively simple to apply heat orother treatment to facilitate the discharge or to change the characterof the wax. And, it will be apparent that in the practice of myinvention all petroleum products including distillates and residues andmixtures may be dewaxed by added to the wax-containing product and itis.

chilled to precipitate the wax and introduced through pipe 6 to thecentrifugal bowl 1. The bowl contains a member '1 having three radialwings and held in position by resilient members 8 and acting to causeliquid to assume the speed of the bowl. Under the influence ofcentrifugal force the oil-solvent solution will 'be segregated at theouter zone of the bowl and passed around the outer edge of the dividingwall 9 thereof and will be discharged through passages 10 (only one ofwhich is shown). The waxwill be segregated in the inner zone of the bowland will pass over the weir ll of the dividing wall 9 and will bedischarged from passages 12 (only one of which is shown). The level ofthe oil-solvent solution is determined by the inner diameter of theringlike weir 13 which is replaceably held in position by the nut 14 andthe radial depth of oil-solvent solution between the inner edge of theweir 13 and the outer edge of the dividing wall 9 will be so adjusted byselection of a weir 13 of proper internal diameter, that that depth ofoil-solvent solution will maintain hydraulic balance with the wax andoil-solvent solution in the main compartment of the bowl. Oil-solventsolution will be collected in the receiving cover 15 and dischargedtherefrom through spout 16 and wax will be collected in receiving cover1'7 and discharged therefrom through a spout 18. To facilitate dischargeof unusually firm or adhesive wax from cover 1'7, there may be providedan annular chamber 19 receiving hot fiuid through pipe 20 and jetting it'through orifices 21, liquid so discharged against the neck of the bowlbeing dispersed in cover 1'7 and thrown against the walls thereof tofacilitate the fiow of wax from the cover. Spout 16 is preferablyprovided with a trap 22 while wax from spout 18 is collected in areceiver 23.

From the foregoing it will be apparent that in accordance with myinvention wax-containing petroleum products may be dewaxed centrifugally with only the simple operations of diluting and chilling aspreparatory steps and that such products may be so dewaxed regardless ofthe nature of the wax-regardless of whether it is crystalline,amorphous, or mixedand regardless of the manner in which the particularpetroleum product was produced.

Examples of the separation of wax from oil that further illustrate myinvention are as follows:

A lubricating distillate of Mid-Continent crude oil-a fraction that istermed slop distillate in commercial practice-was diluted with naphthaand chilled and subjected to centrifugal treatment all in accordancewith the best known previous practice but without successful results,because some of the wax was lighter than the oil-naphtha solution and,perhaps because of the presence of crystalline wax, discharge of waxfrom the bowl ceased. Then petrolatum from Mid- Continent crude oil wasadded in such proportion as to bring the wax content of the distillateto such specific gravity and consistency as to permit centrifugalseparation of the wax, and with the mixture properly chilled centrifugalseparation produced oil having a cold test of 25 F. Then a mixture wasmade of which 30%, by volume, consisted of another quantity of the samelubricating distillate and 70%, by volume, consisted of ethylenedichloride, and this mixture was rapidly a cold test.

Again, light distillate of Mid-Continent crude oil-the fraction between100 seconds and 250 seconds Saybolt Universal viscosity at 100 F. wassimilarly treated. When this distillate was merely diluted with naphthaand chilled and cen-' trifugally treated, all in accordance with thebest known previous practice, the centrifugal separation was notsuccessful. When a proper quantity of petrolatum was added to the oiland it was diluted with naphtha and chilled and centrifugally dewaxed,the final oil product had a cold test of 25 F. A final oil having 0 F.of cold test was obtained when ethylene dichloride was used as a solventin the proportions used in the first example and the chilled mixture wascentrifugally dewaxed, and the wax obtained was so crystalline that itsweated itself out to a hard paraffin. It has heretofore been impossibleto remove such wax from oil by merely diluting and chilling and thenremoving wax by a process dependent upon differences in specific gravitybetween the wax and the solution.

Again, heavy pipestill distillate of Mid-Continent crude oilpracticallya cylinder stock-. was mixed, afterlight acid treatment, that removedhard asphalt, with ethylene dichloride in the volumetric proportion of35 to 65 and the mixture was chilled to about 15 F. and centrifugallydewaxed. The oil produced, freed of emylene dichloride, had a cold testof 10 F. and did not cloud at 0 F. The wax obtained had a melting pointof 124 F. V

In the practice of my invention the wax-containing oil is mixed with asolvent of such nature that the wax will be lighter than the remainingsolution after the mixture has been sufficiently chilled to effectprecipitation of the wax. Sufficient solvent is used to insure that themixture will be suificiently liquid after chilling to permit properremoval of wax. When light petroleum products have been used as thesolvent, the mixture has heretofore been chilled to 10 F. or onlyslightly lower for the purpose of precipitating the wax, and even moreextensive chilling has been desirable but has been prevented byeconomical considerations. However, in the practice of my invention, thechilling need only be carried to a point at which suitable precipitationoccurs and I have found that when ethylene dichloride is employed as asolvent, a lower cold test oil is obtained by centrifugal separationfrom a mixture that has been chilled to 15 F. than could be obtained ifa' wax-containing oil had been chilled to 10 F. in connection withtheuse of naphtha as a solvent.

It will be apparent from the foregoing that in accordance with myinvention wax-containing petroleum products may be dewaxed to a degreehigher than that previously attained in commercial practice and bysimple steps, and that the procedure is effective independent of thecharacter'of the wax that is'to be removed. It is to be noted, however,that important advantages of my invention that are obtained withoutregard to the manner in which the wax is actually removed fromthechilled mixture.

The use and advantages of solvents heavier than wax in the separation ofwax from oil, particularly by processes depending upon differences ofspecific gravity between wax and oil-solvent mixtures, constitute thesubject matter of thistate formed by chilling the solution ofwax-containing oil is not, strictly speaking, ere'wax but comprises wax,oil and solvent; and theresidual liquid in which the precipitate isformed comprises both oil and solvent and sometimes contains someresidual wax-that is not precipitated. Accordingly, it is to beunderstood that the reference herein to precipitated. wax is intended asa reference to a precipitate of the character above mentioned; andreferences herein to oil are intended to include both oil and solutionsof oil, which may also containlwax.

I claim:

1. In the production of dewaxed lubricating and distillates obtainedfrom wax-containing mineral oil, the steps comprising mixing awaxcontaining lubricating-oil fraction with dichlor ethane, cooling themixture to a temperature at which wax precipitates/land oil and thesolvent remain liquid, separating precipitated wax from the cooledmixture by centrifugal. subsidence, and separately dischargingcontinuously from the centrifuging operation wax and clear solution ofdewaxed oil.

2. In the production of dewaxed lubricating oil from wax-containinglubricating-oil residues and distillates obtained from wax-containingmineral oil, the steps comprising mixing a waxcontaining lubricating-oilfraction containing amorphous wax wth dichlor ethane, cooling themixture to a temperature at which wax including amorphous waxprecipitates and oil and the solvent remain liquid, separatingprecipitated wax from the cooled mixture by centrifugal subsidence, andseparately discharging continuously from the centrifuging operation waxand clear solution of dewaxed oil.

3. In the production of dewaxed lubricating oil from wax-containinglubricating-oil residues and distillates obtained from wax-containingmineral oil, the steps comprising mixing a waxcontaining lubricating-oilfraction \1 containing crystalline wax with dichlor'ethane, cooling themixture to a temperature at which wax including crystalline waxprecipitates and oil and the solvent remain liquid, separatingprecipitated wax from the cooled mixture by centrifugal subsidence. andseparately discharging continuously from the centrifuging operation waxand clear solution of dewaxed oil. 3

4. In the production of dewaxed lubricating oil from wax-containingfractions of mineral oil, the steps comprising mixing the wax distillateof crude wax-containing petroleum with an oil solvent containingsufiicient dichlor ethane to cause the resulting solvent-oil solution topossess a specific gravity higher than that of wax precipitated in themixture by cooling thereof,

cooling the mixture to a temperature at which wax precipitates thereinand oil and the solvent remain liquid, separating precipitated wax fromthe cooled mixture by'centrifugal subsidence, and separately dischargingcontinuously from the centrifuging operation wax and clear solution anddistillates obtained from the wax-containing mineral oil, the stepscomprising forming a mixture of the wax-containing oil and an oil-.

solvent containing suflicient dichlor ethane to causethe resultingsolvent-oil solution to possess a specific gravity higher than that ofwax precipitated from the mixture by cooling, cooling the mixture toa'temperature not substantially below that at which the wax isprecipitated to a desired degree, separating precipitated wax from thecooled mixture by centrifugal subsiilence, and separately dischargingcontinuously from the centrifuging operation wax and clear solution ofdewaxed oil. 1

6. In the production of dewaxed lubricating oil from wax-containinglubricating-oil residues and distillates obtained from wax-containingmineral oil,'the steps comprising forming a mix-- ture of the waxcontaining oil and an oil-solvent containingsufiicient dichlor ethane tocause the I L resulting solvent-oil solution to possess a specific oilfrom wax-containing lubricating-oil residues gravity higher than that ofwax precipitated from the mixture by cooling, cooling the mixture to atemperature not substantially below that at which the waxis'precipitated to a desired degree, 7 and separating precipitated waxfrom the cooled mixture to produce clear solvent-oil solution.

7. In the production of dewaxed lubricating oil from wax-containinglubricating-oil residues and distillates obtained from thewax-containing mineral oil, the steps comprising adding to thewax-containing oil a solvent which comprises dichlor ethane and apetroleum fraction lighter than the oil to be dewaxed, said solventhaving such specific gravity and being added in such proportion that theresulting solvent-oil solution will posses a specific gravity greaterthan that of wax precipitated in the mixture by cooling, cooling themixture to a temperature at which wax precipitates and the oil andsolvent remain liquid, andseparating precipitated wa'x from the mixtureand thereby producing clear solventoil solution.

8. In the production of dewaxed lubricating oil from wax-containinglubricating-oil residues and distillates obtained fromwax-containingmineral oil, the steps comprising adding to thewax-containing oil a solvent mixture comprising dichlor ethane and ahydrocarbon that remains liquid at all temperatures encountered in thewax-separating operation, the solvent mixture being added in suchproportion that the resulting solvent-oil solution has a specificgravity greater than that-of wax precipitated by cooling of the mixture,and separating wax from the cooled mixture and thereby producing clearsolution of dewaxed oil. I

9. A method for producing dewaxed residual lubricating oil having a pourtest of substantially 0 F. from wax-containing petroleum which com-=prises mixing a residue of wax-containing petroleum with a solventcomprising a dichlor ethane, the solvent having such specific gravityand being present in such proportion that the specific gravity of thesolvent-oil solution is greater than that of wax precipitated in themixture by cooling, cooling the mixture to a temperature at which wax isprecipitated ,to a desired degree while the oil to be dewaxed remains insolution in the solvent, separating the precipitated wax from the cooledmixture, and separating the solvent from the dewaxed solvent-oilsolution and thereby producing dewaxed, natural, re-

sidual lubricating oil having a pour test of 0 F. to 10 F.

10. A method for producing natural, dewaxed, lubricating oil having apour test of substantially 0 F. from distillates and residues ofwax-containing petroleum; which comprises mixing a substantiallyuncracked fraction of 'zwax-contain-f ,ing'petroleum with an oil-solventcomprising,

dichlor ethane, said solvent having such specific gravity and beingpresent in such proportion that the resulting solvent-oil solution has aspecific gravity greater than that of wax precipitated in the mixture bycooling, cooling the mixture to a temperature at which wax isprecipitated to a desired degree while'the oil to be dewaxed and thesolvent remain liquid, separating precipitated wax from the cooledmixture, separating the solvent from the dewaxed solventoil solution andthereby producing natural, dewaxed lubricating oil having a pour. testbetween 11. 'In the production of dewaxed lubricating oil fromwax-containing lubricating-oil residues 0F. and 10 F. from waxcontaining petroleum and distillates obtained from the wax-containingmineral oil, the steps comprising forming a mixture of thewax-containing oil and sufiicient of an oil solventof the groupconsisting of dichlor

